Boiler



,Jlme 5, 1962 R. Goss/ALTER 3,037,490

BOILER Filed July l5, 1960 Unite tates The present invention relates to a boiler in which two liquids, such as tap water and water for a central heating installation, flowing through two separate exterior systems, are heated by surfaces in turn heated by the flame or the combustion gases and in which heat exchanging surfaces are provided inside the boiler which enable the heat to be exchanged between the two liquids.

Boilers for the simultaneous heating of the heat carrier for a central heating plant and of tap water are Well known, but in the known designs only the heat carrier for the central heating plant is heated by the heating surfaces in direct contact with the heating gases, while the tap water in turn is heated only by the former heat carrier through the intermediary of heat transmitting surfaces arranged between the said two liquids. T ransmission of heat from the water or other heat carrier in the central heating plant is accompanied by a temperature drop dependent on the efficiency of heat transfer, so that the ltap water always obtains a temperature, depending on the consumption, lower than the heat carrier of the central heating. This is often undesirable, `and the tap water must be additionally heated by further electrically or gas operated boilers. Furthermore, very large surfaces are required in the heat exchangers in order to keep the temperature drop between the heat carrier of the central heating plant and the tap Water as small as possible. If heating water is used only during a few hours of the day, large reservoirs are provided in many cases which are heated during periods of small consumption with comparatively low transfer effects.

In addition to the reservoir losses, considerable losses due to the large exterior surface are involved. The reservoirs must be designed so as to produce the maximum daily consumption, with the result that very often hot water is kept in the reservoir which is not needed. Extended storage of the water when hot detrimentally affects the taste.

In other known designs the heating surface is formed by small heating coils of tubes of small diameter. If the water employed is hard, deposits will form on the interior surfaces of these tubes after a short time, which Will increase the resistance to heat transfer. These deposits of'ten cause obstructions in the tubes with all their dangerous consequences. Since the advent of oil-burning heating systems, the known heating installations also suffer from the consequences of corrosion which ensues from the condensation deposits of the waste gases. These deposits occur mainly on heating surfaces which are cooled by the cold returning water; boilers made of cast iron or steel may be destroyed by these corrosion effects in a matter of years.

One of the main objects of the invention is to provide a design in which the tap Water and the water or other heat carrier for the central heating plant can be heated in a single boiler while eliminating the disadvantages of the systems so far known.

According to one aspect of the invention, a doublewalled arne tube is provided in a boiler of the design first cited, the said tube being arranged in a smoke llue designed `as a cup while the boiler Walls are double, connection being provided between the space formed by the double walls of the boiler and the interior of the flame tube, and with a heat exchange jacket extending over only part of the length of the double walls of the boiler,

arent while the space located between the inner wall of the boiler and the heat exchange jacket is connected with a space enclosed by the smoke flue and the inner boiler wall and, respectively, heat exchange jacket.

The invention will be described in greater detail in conjunction with the attached drawing which shows a longitudinal section of a boiler.

The boiler generally designated at 1 rests on two supports 2 and 3. The boiler consists of an outer insulating jacket 4 of which one side is connected with a closing member 5. The closing member 5 is provided with a central opening 6 through which the burner 7 extends into the interior of the boiler. The burner may be removably attached to the member 5 as by a flange 8.

The boiler 1 is designed to heat the heat carrier and tap water, a separate circulation system being provided for each. Directly adjacent to the insulating jacket 4 is a first Water jacket 9 for the heating water. The jacket 9 is connected with a supply connection or heating water inlet 10 in turn communicating with a supply Vline 11 for the heating water. The hot-water jacket 9 is composed by an outer wall and an inner wall 12. The water which enters the hot-water jacket 9 through the supply connection 10, leaves it through. the connection 13 which in turn communicates, via a line 14, with the hollow interior space of a flame tube 15.

Inside the wall 12, a space 16 for the tap water is provided. The space 16 is closed on the inside by a boundary wall 17 which also constitutes the outer boundary of the actual combustion chamber. An annular portion of the space 16 adjacent to the wall 12 is separated from the rest 'of the space 16 by a heat exchange wall 18 and designed to preheat the tap Water; it is connected with a supply tube 21 while the heat exchange wall 18 is provided -with an opening 22 through which the water in the space 20 can p-ass into the rest of the space 16.

The combustion chamber 23 delimited by the wall 17 accommodates a conical flame tube 15 formed of two concentrically arranged conical Wall portions 25 and 26. The space between the two wall portions holds the heating water. 'llo this end, Ithe hollow ame tube 15 is connected with a tube length 24 which forms the connection with the line 14. ln addition, a delivery tube 27 is provided. Provided on the inside of the Wall 26 are inclined baffle plates shown diagrammatically at 28, which cause tur# bulence in the combustion gases so as to establish a close heat-exchanging Contact with the Walls 17, 26 and 25. As the drawing shows, the combustion gases pass, as indicated by arrows, from -the interior of the flame tube 15 into the space between the wall 17 and 25. This annular space is connected to a flue (not shown).

The hea-ting water leaving the connection 27 passes, Via a chamber 30, to the heating system diagrammatically indicated at 31, the flow volume being adjustable, by way of example, lby a valve diagrammaticallyshown at 32. The returning Water passes 4into the supply line 11 from a chamber 33 and through an injector nozzle 34. As generally known, the injector nozzle causes a nega-tive pressure to be formed in the enclosing space 30 Which in turn causes a portion of the hot heating water emerging from the `connection 27 to be sucked into the line 11. As a consequence thereof, the cold heating Water supplied is warmed, which reduces the danger of corrosion.

The heating water 11 supplied first reaches the jacket 9, as descri-bed above, where it is indirectly warmed by the tap Water held in the space 16. The warmed water then passes, via the line 14, into the interior of the flame tube 15 where it is heated to the final temperature. Owing to the preheating of the heating water, the latter is prevented from causing condensate on the walls 25 and 26 `forming the flame tube. Such condensation would, as

3 stated at the outset, greatly assist erosion processes which can result in the destruction of metal parts after a short time.

The tap Water entering through connection 21 will not directly contact a wall which is impinged by the combustion gases, it is first preheated. As described above, the annular space 20 is provided for this purpose. This annu= lar space is heated from both sides, i.e. by both the jacket 9 and the space 16, so that the tap Water emerging through opening 22, which then establishes contact with the wall 17, is already preheated. The tap water leaves the space 16 through connection 21 after being heated to the final temperature by contact with the wall 17.

In the boiler' shown, the wall 18 performs two functions. On the one hand it is designed to preheat the cold water before it is heated directly by the combustion gases; on the other hand, it protects the boiler against corrosion by the fresh water supplied.

There are areas in almost every country in which the water contains corrosive components; water tanks can be destroyed by such components in a short time. This can be avoided by appropriate processing of the water by means of chemical additions, but this will increase costs. In the design of the boiler shown, the wall 18 is the member most subjected to corrosion. However, this wall caneasily be replaced and it is not costly. Even if this wall were completely destroyed, no danger whatever exists for the other members of the boiler, which remains fully operative. If the wall, or exchange jacket, is destroyed, the water entering through connection 11 leaves the boiler through connection 21 without being heated, which immediately reveals that the wall 18 has been damaged by rust; this condition can easily be remedied at small cost by replacing `the wall.

For the purpose of further supervision, a thermometer 22' may, if necessary, be provided to enable the temperature of the water iiowing out of the opening 22 to be continuously checked.

Having now particularly described and ascertained the nature of my said invention and the manner in which the same is to be performed, I declare that what I claim is:

l. In a boiler for heating tap water and water for a central heating plant, a tubular jacket having an inner and an outer side wall and inner and outer end walls confining a space therebetween, a boundary wall having side and end walls arranged within said inner walls of said jacket and with said inner walls of said jacket confining a space therebetween, an open ended flame tube extending inside said boundary wall in spaced relationship thereto, said flame tube being composed of an inner and an outer wall confining with each other a hot water receiving chamber, said boundary wall confining with the outer wall of said ame tube a passage for hot gases for heating the outside of said flame `tube and the inside of said boundary wall, a burner arranged on the inside of said flame tube for heating the inner wall thereof and to pass hot gases through said passage to thereby heat the outer wall of said ame tube and said boundary wall, a water inlet connected to said tubular jacket for water of said central heating plant, conduit means connecting said tubular jacket with said chamber between `said inner and said outer wall of said flame tube, a water outlet connected to said chamber, a tap water outlet connected to said space between said inner walls of said jacket and said boundary wall, and a heat exchange wall connected to said inner side wall of said jacket and confining an annular chamber therewith adjacent said inner side wall of said jacket, a tap water inlet connected to said annular chamber, said heat eX- change wall being provided with an opening effecting communication between said annular chamber and said space between said inner walls of said jacket and said boundary wall, said opening being spaced from said tap water inlet so that the water from the tap water inlet is heated in said annular chamber prior to entering said space between said inner side wall of said jacket and said boundary wall.

2. In a boiler for heating tap water and water for a central heating plant, a tubular jacket having an inner and an outer side wall and inner and outer end walls confining a space therebetween, a boundary wall having side and end walls arranged within said inner walls of said jacket and with said inner walls of said jacket confining a space therebetween, an open ended flame tube extending inside said boundary wall in spaced relationship thereto, said flame tube being composed of an inner and an outer wall confining with each other a hot water receiving chamber, said boundary wall confining with the outer wall of said flame tube a passage for hot gases for heating the outside of said ame tube and the inside of said boundary wall, a burner arranged on the inside of said ame tube for heating the inner wall thereof and to pass hot gases through said passage to thereby heat the outer wall of said flame tube and said boundary wall, a water inlet connected to said tubular jacket at one side for water of said central heating plant, conduit means connecting said tubular jacket at the other side with said chamber between said inner and said outer wall of said flame tube, said fiame tube and said boundary wall being conically shaped and substantially coaxial with each other, the end of said fiame tube having its larger diamcter accommodating said burner, a water outlet connected to said chamber, a tap water outlet Connected to said space between said inner walls of said jacket and said boundary wall, and a heat exchange wall connected to said inner side wall of said jacket and confining an annular chamber therewith adjacent said inner side wall of said jacket, a tap water inlet connected to said annular chamber, said heat exchange wall being provided with an opening effecting communication between said annular chamber and said space between said inner walls of said jacket and said boundary wall, said opening being spaced from said tap water inlet so that the water from the tap water inlet is heated in said annular chamber prior to entering said space between said inner side wall of said jacket and said boundary wall.

3. A boiler according to claim 2, in which that end of said conical i'iame tube which has the smaller diameter -is provided with inwardly projecting batiie plates inclined with regard to the longitudinal axis of said ame tube.

4. A boiler according to claim 1, in which the connection of the space formed by the double wall jacket with the interior of the ame tube is effected by a tube arranged outside the boiler.

5. A boiler according to claim l, in which said tap water inlet and outlet are arranged near one end of said jacket and are separated from each other by said heat exchange wall, and in which said opening in said heat exchange wall is arranged near the opposite end of said jacket.

6. In a boiler for heating tap water and water for a central heating plant, a tubular jacket having an inner and an outer side wall and inner and outer end walls confining a space therebetween, a boundary wall having side and end Walls arranged within said inner walls of said jacket and with said inner walls of said jacket confining a space therebetween, an open ended flame tube extending inside said boundary wall in spaced relationship thereto, said liame tube being composed of an inner and an outer wall confining with each other a hot water receiving chamber, said boundary wall confining with the outer wall of said flame tube a passage for hot gases for heating the outside of said flame tube and the inside of said boundary wall, a burner arranged inside of said ame tube for heating the inner wall thereof and to pass hot gases through said passage to thereby heat the outer wall of said flame tube and said boundary wall, a water inlet connected to said tubular jacket for water of said central heating plant, conduit means connecting said tubular jacket with said chamber between said inner and said outer wall of said flame tube, a water outlet connected to said chamber, a tap water outlet connected to said space between said inner walls of said jacket and said boundary wall, a heat exchange wall -connected to said inner side wall of said jacket and confining an annular chamber therewith adjacent said inner side wall of said jacket, a tap water inlet 6 nozzle through which said inlet heating water passes and `an inductor element having its low pressure side connected to said heating water outlet whereby the inlet heating water is mixed with outlet heating water before connected to said annular chamber, said heat exchange 5 passing into said tubular jacket.

wall being provided with an opening effecting communication between said annular chamber and said space between said inner side wall of said jacket and said boundary wall, said opening Ibeing spaced from said tap water inlet so that the water lfrom the tap water inlet is heated in said annular chamber prior to entering said space between said inner wall of said jacket land said boundary wall, :and inductor means interposed between said heating water inlet and said heating water outlet and establishing communication therebetween, said inductor means having a References Cited in the tile of this patent UNITED STATES PATENTS 

